This device pertains to emergency escape devices for the purpose of evacuating persons from hazardous elevated structures. Petroleum refining plants, chemical process plants, oil and gas production and drilling facilities inherently present hazardous working conditions for personnel. These hazardous conditions may become an immediate emergency should an accidental leakage of toxic fumes of flammable gas or fire occur. History has shown that it is prudent to offer personnel a convenient, fast means of escape during an emergency situation.
Standard ladders and stairways are the only means of escape available at petroleum refining and chemical plants known to this applicant. Onshore oil and gas drilling rigs, again employ standard stairways for personnel working near the ground. A cable/trolley arrangement is used as a means of escape for personnel working at substantial heights. Ladders and stairways are most often located to suit high personnel traffic flow. They do not offer the quickest means of egress and may present an additional risk to personnel during haste to evacuate. Perhaps because of the potential danger and isolation offshore oil and gas production and drilling facilities have received the most attention as related to emergency escape safety devices. These facilities are usually located on platforms which are a considerable distance above water level. Because of this height it is unsafe and impractical for personnel to jump into the water to safety. Alternative means of escape have been invented in recent years.
One such existing device is disclosed in U.S. Pat. No. 4,703,832. It consists of an exit platform to which a rigid pole is attached. The pole is stored horizontally when the device is not in use. To use this system a locking device must be released, which allows the pole to rotate to vertical whereupon personnel then slide down the pole to water level. Because of the great differential in diameter to length ratio of the pole it is subject to be easily deformed and rendered useless. The pole would have to be made of metal because of the strength/rigidity requirements of this arrangement. Metal has very good thermal conductive characteristics. Escaping personnel may not be able to use this device or be injured should the metal pole be exposed to high temperatures. An operator must stand at a remote location, some distance from the exit platform, to deploy and retrieve the pole. This remote operator location may use valuable platform deck space and become inaccessible if obstructed by equipment or supplies. Offshore platforms usually have two or three deck levels. Each deck is usually different in size with perimeters offset vertically. This system is not compact and may be difficult to locate on a platform because of offset decks and the inordinate area needed to rotate the pole from horizontal to vertical position. Another system is U.S. Pat. No. 4,202,427. It comprises an A-frame which is attached to the drilling rig or production platform. An escape capsule, which is a water-tight vessel, is suspended by wire cables from this frame. During an emergency personnel enter the capsule, then must activate a release mechanism. The frame and capsule will then pivot outboard allowing the capsule to descend by the cables, at a controlled rate of speed, to the water level. This apparatus is expensive, which may limit the number installed on a given platform, or the singular installation on a platform with few people. These capsules have limited seating capacity, which is undesirable considering the variable quantity of personnel on offshore platforms. A shortage of seating space may create panic, which may jeopardize the entire escape attempt.